第二十一课

21  How fast an object moves物体运动的快慢

1. In the sports meeting, students are running a race.运动会上，同学们正在进行赛跑，

2. How to know who is running fast?怎样知道谁跑得快呢？

3. Materials package: tape measure, etc.材料包：卷尺等

4.  Activity process活动过程

5. Measure and compare who is running faster.测一测，比一比谁跑得快。

6. Thinking navigation思维导航

7. When the distance is the same, how to determine who is running faster?距离相同时，怎样判断谁跑的快？

8. How to judge who is running faster when the practice is the same?实践相同时，怎样判断谁跑的快？

9. When the distance and time are different, how can you tell who is running faster?距离和时间都不同时，怎样判断谁跑到快？

10. The speed of an object's movement can be described by the magnitude of its speed.物体运动的快慢可以用速度的大小来描述。

11. The common units of speed are km/h and m/s.速度的常用单位有千米/时、米/秒。

12. When we go out for a trip, which transport is more suitable for us to choose?外出旅游，我们选择哪种交通工具更合适呢？

13. I read from the information that the speed of high-speed trains is ------我从资料上看到，高速列车的速度是······

14. From Beijing to hurt, I choose to take the high-speed train.从北京到伤害，我选择乘坐高速列车。

15. Extension activities拓展活动

16. Check the train schedules and the distances between places along the railroad line.查阅列车时刻表及铁路沿线各地之间的距离，

17. Analyze it and tell us what you found.分析一下，说说你的发现。